Specific Heat of a Metal
One physical property of a pure substance is the amount of heat energy it will
absorb per unit of mass. This property can be measured quite accurately and is
called specific heat (Cp). Often applied to metallic elements, specific heat is the
amount of heat energy, measured in joules, needed to raise the temperature of one
gram of the substance one degree Celsius.
To measure specific heat in the laboratory, a calorimeter of some kind must be
employed. A calorimeter is simply a well insulated container used to reduce the
loss or gain of heat energy from the surrounding room conditions. Heat energy
always flows from a body at a higher temperature to a body at a lower temperature. The heat gained by the cooler substance equals the heat lost by the warmer
substance if we assume no loss of heat to the surrounding environment.
A metal sample will be heated to a high temperature then placed into a
calorimeter containing a known quantity of water at a lower temperature. Having
measured the mass of the water in the calorimeter, the temperature change of the
water (A T), and knowing the specific heat of water (4.184 J/g - CO), the heat gained
by the water (lost by the metal) can be calculated as follows:
Specific heat
Mass of
Heat gained by
= Water (g) x AT (CO) x of water (4.184 J/g • CO)
the water
From the measured heat lost by the metal, the specific heat of the metal can be
calculated as follows:
Specific heat =
of metal (Cp)
Heat gained by the water
Mass of metal (g) x AT of metal (CO)
Objective
In this experiment, you will determine the specific heat of a metal sample.
Equipment
250 mL beaker
styrofoam cup
thermometer
18 x 150 mm test tube
Procedure
1. Fill a 250 mL beaker about half full with tap water.
2. Place the beaker of water on a ringstand with wire gauze.
Begin heating to boiling.
3. Measure the mass of an empty, dry 18 X 150 mm test tube and
record.
4. Add the sample metal pieces until the test tube is half-full.
Record the mass of the test tube and metal.
5. Place the test tube containing the metal into the beaker of
water as shown in Figure 3-1 and continue heating the water to
the boiling point.
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6. Obtain a styrofoam cup to be used as a calorimeter and measure the mass carefully. Record.
7. Fill the styrofoam cup about half-full with distilled water at
room temperature and record the mass.
8. After the water in the beaker containing the test tube with the
metal has boiled for several minutes, measure the temperature
of the water with a thermometer and record. (It will be assumed the temperature of the metal is the same as the boiling
water.)
9. Measure the temperature of the water in the styrofoam cup
and record.
10. Remove the test tube containing the metal from the boiling
water and immediately dump the metal into the styrofoam
cup.
11. Stir the water in the styrofoam cup sloiidv (thermometers can
he broken easily), then record the highest temperature
reached.
12. Recover the metal by carefully pouring the water off (decanting), then spread the solid metal on a paper towel to dry. Do
FIGURE 3-1. Apparatus set-up for boiling a liquid such as water.
not let any metal particles get into vour laboratory sink.
13. Repeat entire procedure with a different metal ii time permits.
Data
The following table will help to organize your data. In future
experiments, you will need to design your own table:
I. Mass of test tube empty
2. Mass of test tube + metal
g
3. Mass of styrofoam cup
4. Mass of styrofoam cup + water
g
g
g
5. Temperature of boiling water
"C
6. Temperature of water in cup
7. Temperature of water in cup after metal
was added
"C
°C
Calculations
1. Calculate the heat gained by the water (lost by the metal) in the
calorimeter using the equation in the Introduction.
2. Calculate the specific heat of the metal using the answer from
Calculation 1 and the equation in the Introduction.
Questions and Problems
1. Why is water an excellent material to use in a calorimeter?
2. Calculate the specific heat of a metallic element if 50.0 g of the
metal need 314 joules of heat energy to raise the temperature
from 25°C to 50°C.
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